Cerebral palsy (CP) is one of the most prevalent and costly pediatric neurologic conditions diagnosed in the United States. Despite years of studies that have catalogued the motor impairments seen in children with CP, innovative and effective interventions have not emerged. At least part of the problem is that the majority of treatment approaches (e.g., surgical, stretching, strengthening) emphasize the musculoskeletal impairments that may affect the execution of the movement pattern, without attention to the abnormalities in sensorimotor cortical activity, which underlie the motor planning and programming that children with CP use to perform and learn motor tasks. Addressing this substantial gap is paramount, and central to our long-term research goals of developing innovative treatment strategies that have the highest probability of teaching children with CP new motor skills. To meet this goal, we have implemented an innovative scientific approach that uses high-density magnetoencephalography (MEG), diffusion-tensor imaging, and advanced human movement analysis methods to identify the neurophysiological factors that influence a child with CP's motor performance. The Specific Aims of this proposal will (1) determine how the stage-like beta and gamma sensorimotor cortical oscillations are modulated by intensively practicing a goal-directed motor task, (2) quantify how activity within the somatosensory cortices affects the sensorimotor integration processes that are necessary for learning a goal-directed motor task, and (3) quantify the relationships between the extent of activation within the sensorimotor cortices, motor behavioral improvements, and the integrity and quantity of fibers in the thalamocortical and corticospinal tracts. Briefly, our study will address these aims by quantifying the neurophysiological and motor behavioral changes that occur after practicing an isometric ankle plantarflexion target matching task. We will focus on an ankle motor task because control of the ankle joint is well recognized as playing a key role in the mobility and postural limitations seen in children with CP. Our study design consists of the collection of MEG and motor behavioral measures prior to training (baseline), after 3- days of intensive training, and a week after cessation of the training. Participants will include a cross-section of children with CP that have various levels of motor impairments (e.g., GMFCS I-IV), and a cohort of age- matched typically-developing children. Outcomes from the proposed experiments will be seminal for challenging and potentially redirecting the current rehabilitation methods that are used to teach children with CP new motor skills. Furthermore, we expect that the new neural indices of motor learning established in this proposal will provide critical insight on why some children with CP show vast improvements after therapy, whereas others are classified as non-responders. Understanding the neural mechanisms that may limit the progress of non-responders will enable us and other research groups to develop new individualized treatment strategies that will allow for all children with CP to have the best chance of learning new motor skills.